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The American Association of State Highway and Transportation Officials (AASHTO) is a standards setting body which publishes specifications, test protocols, and guidelines that are used in highway design and construction throughout the United States. Despite its name, the association represents not only highways but air, rail, water, and public ...
The primary US guidance is found in A Policy on Geometric Design of Highways and Streets published by the American Association of State Highway and Transportation Officials (AASHTO). [2] Other standards include the Australian Guide to Road Design Archived 2011-11-09 at the Wayback Machine, and the British Design Manual for Roads.
The route numbers and locations are coordinated by the American Association of State Highway and Transportation Officials (AASHTO). [4] The only federal involvement in AASHTO is a nonvoting seat for the United States Department of Transportation. Generally, most north-to-south highways are odd-numbered, with the lowest numbers in the east and ...
Since the policy on numbering and designating US Highways was updated in 1991, AASHTO has been in the process of eliminating all intrastate U.S. Highways under 300 miles (480 km) in length, "as rapidly as the State Highway Department and the Standing Committee on Highways of the American Association of State Highway and Transportation Officials ...
The results from the AASHO road test were used to develop a pavement design guide, first issued in 1961 as the AASHO Interim Guide for the Design of Rigid and Flexible Pavements, with major updates issued in 1972 and 1993. More recent versions of the guide are not primarily based on the results of the AASHO Road Test.
The AASHTO Soil Classification System was developed by the American Association of State Highway and Transportation Officials, and is used as a guide for the classification of soils and soil-aggregate mixtures for highway construction purposes.
Recovery areas: There should be no fixed objects in the clear zone, the width of which should be determined by the design speed in accordance with the current edition of AASHTO's Roadside Design Guide. When this is not possible, breakaway supports or barriers guarding the objects should be used. Special care should be taken in depressed ...
The definition in the 1994 edition of the AASHTO Green Book, [10] was "the maximum safe speed that can be maintained over a specified section of highway when conditions are so favorable that the design features of the highway govern. The assumed design speed should be a logical one with respect to the topography, the adjacent land use, and the ...